Low input pilot burner



April 1, 1958 R. B. LARKIN, .IRv 2,828,814

Low INPUT PILOT BURNER Filed April' 12, 1955 F. @2f el @265m @maggy l Arron/v l nite tes Patent i" LOW INPUT PILT BURNER Robert B. Larkin, Jr., Bay Village, Ohio, assignor to The Patrol Valve Company, Cleveland, Ohio, a corporation of Ohio This invention relates to constant burning gaseous fuel pilot burners, and more specifically, to low input pilot burners adapted to be used on gas ranges of the type commonly used in kitchens of homes, where it is highly desirable to keep the amount of heat generated by a pilot ame at the lowest possible level.

Constantly burning pilot burners presently in use on gas ranges, and various gas burning equipment require at least 200 B. t. u. per hour input and frequently require a much larger input. The desirability of providing a pilot burner operating at appreciably lower B. t. u. input is readily understood, however, when pilot burners operating on a relatively low B. t. u. input of from 50 to 100 have been tried, they have been found to be too unstable to withstand the drafts and disturbances to which they may be subjected in normal usage. l have discovered a pilot burner capable of satisfactory pilot operation, even when the gas input is as low as 50 B. t. u. per hour.

Therefore an object of this invention is to provide a stable low-input pilot burner adapted for use on gas range burners, and the like. More specifically, to provide a low input burner operating within an input range of 50 to l0() B. t. u. per hour.

Other objects are to provide a stable pilot burner device, which is readily visible when burning, may be produced ,40

at a relatively low cost, is efficient in operation, is quickly installed, readily adjustable and is simple, reliable and durable in operation.

These and other objects will be apparent during the course of the following description:

In the drawings forming a part of this specification;

Fig. l is a top view of a gas range, partly cut away to show the arrangement of the range burners, the pilot.

burner and associated parts;

Fig. 2 is an elevational view, partly in section of the top 50 of one illustrative form of pilot burner;

Fig. 3 is a top plan view of Fig. 2 taken on the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary sectional view of part of a range burner and a pilot burner adapted to ignite the range burner directly without the use of flash tubes;

Fig. V5 is a side view of the wire used in the pilot burner illustrated in Figs. 1, 2 and 3;

Fig. 6 is a top view of the wire shown in Fig. 5;

Fig. 7 is a side view of a modified type of pilot burner flame stabilizing wire;

Fig. 8 is a top View of the wire shown in Fig. 7;

Fig. 9 is a side view of another type of pilot burner wire;

Fig. l0 is a top view of the wire shown in Fig. 9;

Fig. ll is a side view of another type of pilot burner wire;

Fig. l2 is a top viewof the wire shown in Fig. ll;

Fig. 13 is a side view of another type of pilot burner wire, while Fig. 14 is a top view of the wire shown in Fig. l3.

In the drawings the numeral 15 indicates the top surface of a gas cooking range supplied with gas of any suitable nature, through gas supply conduit 16 connected to a source of gas, while four gas valves 17 control the ow of gas through four cooperating Bunsen burner tubes 18 providing primary-aerated air-gas mixture to each cooperating range burner 19. A constant burning non-prmary-aerated pilot burner 20, disposed centrally of the burners 19, receives a supply of gas through pilot supply conduit 21 from gas supply conduit 16, the ow of gas therein being regulated by pilot valve 22 in a well known manner.

The pilot burner construction illustrated in Figs. l, 2, 3, 5 and 6 comprises, a vertically disposed cone-shaped burner head 23 provided at its top with a small aperture or port 23a, which may vary in diameter from .025" to .050". The burner head 23 is provided interiorly with screwthreads 24 engaging mating threads 25 disposed around the top of the upwardly projecting portion of pilot supply conduit 21 for retaining the head 23 at the top of the conduit 21 as shown in Fig. 2.

A llame stabilizing wire 26, illustrated in Figs. l

through 6 includes a'straight upwardly extending part 27 projecting upwardly through the port 23a, and terminating at its lower end in a fiat looped portion 28, which l is retained against the top margin of the supply conduit 21 by the sloping shoulders 29 of the pilot burner head 23 as shown in Figs. 2 and 4.

The flame stabilizing wire 26 can be formed of any material which will remain solid at the llame te1nperatures reached, and will not be corroded by the combustion products and, at the same time, will not retard the combustion of the gas, during operation of the pilot. In actual use the upper portion of the wire 26 becomes red hot. If the diameter of the wire 26 is too large it does not become red hot and consequently the wire' has a cooltively unstable to winds and drafts. The maximum diamj eter of the flame stabilizing wire 26 will depend upon the B. t. u. input of the pilot, but I have found that for 1 pilots having inputs of 50 to 100 B. t. u. per hour, wires of diameters of .013 to .030 are satisfactory.

It has been discovered that any solid material having the properties previously set forth is satisfactory. However, I have found that platinum alloys, and alloys containing nickel and/or chromium are superior. Except for structural purposes, filaments of silicon or quartz are satisfactory. Thin wires or filaments of these materials are effective because of the catalytic action of Pt, Ni, Cr, Fe or SiO2-combustion and because of the radiant energy emitted to the unburned gas by the red hot substance. It has been found that the wire 26should not'extend above Vthe top of the pilot flame 33 vto a height greater than the length of the flame 33, i. e., the length of the wire 26 above burner port 23a should not exceed twice the height of the pilot llame 33. If it is higher, it conducts sufficient heat from the flame to cause carbon de# posits to form gn the wire 26.

Flash tubes 30, connecting the main range burners 19 to the centrally disposed pilot burner 2t), are supported at their inner ends by a pilot assembly ring 31, and at their outerends are supported by flash ports 32 projecting from the sides of the range burners 19. The operation of the pilot burner 20 through the Hash tubes 30 to ignite the range burners 19, is controlled by the operator operiing one of the gas valves 17 at the front of the range leading tothe particular range burner 19 which is to be ignited, whereupon a small volume of gas is directed Upon igniting the pilot burner 20 a flame 33 burns around the ame stabilizing wire 26, as illustrated in Figs. 2 and 4, the wire T56' preferably being disposed centrally of the pilot burner port 23a and projectingupwardly a short distance as shown. The wire 26' wiilj soon be heated to a cherry red glow, which functions as an indicator to enable the user to readily/.determine that the pilot burner 20 is burning. ln the absence of such a red glowing wire 26 it is often difficult for the operator to determine whether or not the pilot burner 20 is lighted. The red glow of such wire 26 is readily distinguishable at a distance and presents a novel advantage of my invention. The wire 26 should be sufficiently small to be heated to red hot by the pilot flame 33 over a portion of its length. It is believed that the wire 26 acts as a draft breaker for any drafts blowing against it from any direction, as the flame on the lee side of the wire 26 will be maintained even though the flame on the windward side has been blow off.

It is common knowledge, that under stable ame operating conditions, there is a certain cohesive attraction of the outer mantle of the flame to the periphery of the port, therefore the larger the periphery, the greater is the stability of the flame. Thus, the use of the wire projecting outwardly through the pilot port will permit the use of a port of larger diameter, thus providing more circumference without too much area unbalance with the rate of gas ow.

In general practice today a 72 drill size orifice is used for a pilot burning 250 to 300 B. t. u. per hour. This provides the proper velocity to produce the required flame characteristics and stability under service conditions. Assuming that a 72 drill size orifice is correct for 250 B. t. u. and that one desires to find the proper size for a 50 B. t. u. per hour pilot, comparison may be made on the basis of B. t. u./hr./sq. in. of orifice. Since the area of a 72 drill size orifice is .00049 it is found that by dividing 250 B. t. u.

510,000 B. t. u./sq. in./per hr. are passed. It would then follow that to retain this rate at 50 B. t. u. per hour input it will only require or .000098 sq. in. orifice. The nearest commercial drill to this is a No. S drill with area of .000143 anda diameter of .0135. Such a drill is very difficult to use in volume production. Now if one inserts a .021" dia. wire through an orifice, an orifice can be used which is equal to the sum of area of the cross section of the wire plus the required free area of an orifice for a 50 B. t. u. pilot. In the' case of the .021 wire having an area of .000346-j-.000143 or .000489 sq. in. total area, which is equivalent to a 72 drill.

Thus, it will be understood that the diameter of the pilot port used in this invention is such that it can be readily drilled, and provides the maximum circumference without excessive area. Depending upon the size of pilot flame desired, wire diameter and orifice sizes can be varied to accommodate the demands for increasing the stability of the flame. Thus it is evident from the foregoing that economy in production is accomplished.

In Fig. 4 the type of pilot burner corresponds with the pilot burner illustrated in Figs. l and 2, except that the pilot burner is'positioned directly at the side of a range burner 19a having a series of vertically disposed ignition Y ports 191i adapted to carry the ame 33from the pilot burner 20 up to the top ports of the range burner 19a. For certain purposes it maybe found to be advantageous to provide a separate pilot burner for each range burner for providing positive ignition, without the use of flash tubes connecting the range burner to a central constantly burning pilot burner. The low input rating of this invention lends itself to such types of multiple pilot burners.

The modified form of the invention disclosed in Figs. 7 and 8 discloses a wire 26a having its vertically extending portion crimped to provide greater heating surface.

,Y The Wire 26a may be of the same material as the previously described wire and is similarly retained in the pilot conduit 21, by the shoulders 29 of the pilot head 23a.

The modification disclosed in Figs. 9 and l0 using a coiled wire 2Gb, provides further increase in heating surface and greater draft break and also acts as an increased flame spreader.

The forms shown in Figs. 1l through 14 using one or more wire coils 26C and 26d provide two wires through the pilot oriice requiring a much larger orifice and provide greater wind resistance.

All forms of the invention may be secured to the pilot burner port as shown, or may be otherwise suitably secured thereto, as by spot welding or the like. It will be apparent to those skilled in the art that the invention, shown and described herein, may be variously changed, used or modified without sacrificing the advantages of the invention or departing from the spirit thereof, and that this embodiment of my invention is illustrative only and that my invention is not limited thereto.

I claim:

1. A gaseous fuel low input pilot burner comprising, a pilot burner head having a port opening substantially within the range of .025 inch to .050 inch, and a iiame stabilizing wire having a diameter within the range of .O13 to .030 inch axially disposed in said port opening and projecting outwardly therethrough.

2. A gaseous fuel low input pilot burner comprising, a pilot burner head including a port opening having a diameter within the range of .025 to .050 inch and a flame stabilizing wire having a diameter within the range of .013 to .030 inch and means for retaining said wire within said head said wire having a portion projecting through and extending outwardly from said port.

3. A pilot burner comprising a pilot burner head having a-.port opening substantially within the range of .025 inch to .050 inch, and a flame stabilizing wire disposed axially in said port opening and having a diameter sub-Y stantially within the range of .013 inch to .030 inch, said wire projecting outwardly through and beyond said head adistance substantially corresponding to the maximum Width of said head.

4. Ablue ame pilot burner including readily discernible means indicating the burner is lighted comprising, a burner head having a port opening having a diameter within the range of .025 inch to '.050 inch, and a wire of platinumalloy projecting through said port and axially disposed therein, said wire having a diameter on the order of .021 inch and projecting a substantial distance beyond said port corresponding. to the maximum diameter of said head, wherebythe projecting portion of said wire is heated to a red glow. by a fiame disposed at said port opening providing readily visible means indicating that the pilot burner is lighted.

References Cited in the file of this patent UNITED STATES PATENTS Massier Jan. 26, 1954 

